CFIF statement checking if database (MSSQL) is connecting or exists - coldfusion

Question

I am trying to write an if statement in Coldfusion 16 to check to see if it can connect to the database or that it exists. If it can connect to the database then show the page otherwise show down for maintenance. How should I just check to make sure the database is up? Any help with this would be greatly appreciated.
<cfquery name="DBUP" datasource="datasource">
SELECT ID
FROM dbo.Entry
</cfquery>
<cfif DBUP>
Show Page
<cfelse>
Show Down For Maintenance
</cfif>

Answer 1

You shouldn't directly put a error message or file in a catch statement. We should check one more condition ie) Error code is 0 or not. Imagine in some time the developer may give wrong query like undefined column or missing syntax etc... In that time also the catch will executed. So as per the requirement we have to check the datasource exists or not. If we want to check all type of issue means we no need of the error code conditions.
<cftry>
<cfset showPage = true>
<cfquery name="DBUP" datasource="datasource">
SELECT ID FROM dbo.Entry
</cfquery>
<cfcatch type="database">
<!--- The error code 0 is mentioned Datasource could not be found/exits. --->
<cfif cfcatch.cause.errorcode eq 0 >
<cfset showPage = false >
<!--- Data source does not exists --->
</cfif>
</cfcatch>
</cftry>
Based on showPage value do you business logic here
....
....
....

Answer 2

You will need to add it in Application.cfc onRequest method probably.
<cftry>
<cfquery name="DBUP" datasource="datasource">
SELECT ID
FROM dbo.Entry
</cfquery>
<cfcatch type="any">
Show DOwn For Maintenance
<!---everything optional below this line--->
<!---can show some custom message--->
<cfinclude template="errorMsg.cfm">
<!---stop the processing further--->
<cfabort>
</cfcatch>
</cftry>